Readily disconnectible traffic detector switch and frame having two different size fastening holes



June 1, 1965 R D CULVER READILY DISCONNECTIBLE TRAFFIC DETECTOR SWITCH AND FRAME HAVING TWO DIFFERENT SIZE FASTENING HOLES Filed Oct. 31, 1960 2 Sheets-Sheet l INVENTOR. ROBERT D. CULVER ATTORNEY June 1, 1965 R D CULVER 3,187,138

READILY DISCONNECTIBLE TRAFFIC DETECTOR SWITCH AND FRAME HAVING TWO DIFFERENT SIZE FASTENING HOLES Filed 001;. 31, 1960 2 Sheets-Sheet 2 IN VEN TOR. ROBERT D. CULVER ATTORNEY United States Patent 3,187,138 READILY DESCQNNECTIELE TRAFFIC DETECTOR SWITtIH AND FRAME HAVING TWO DEFFER- ENT SIZE FASTENING HOLES Robert D. Culver, Norwalk, Coma, assignor, by mesne assignments, to Lahoratory for Electronics, 1116., Boston, Mass, a corporation of Delaware Filed Get. 31, 1960, Ser. No. 66,236 5 Claims. (Cl. 200-86) This invention relates to trafiic detector apparatus and more particularly relates to traffic detector apparatus adapted to be embedded in a roadway.

More particularly, this invention relates to means for fastening a treadle switch to a frame which is adapted to be embedded in a roadway.

From one aspect, this invention relates to means for festering a treadle switch to a frame so that the treadle switch may be unfastened from the frame even though the fastening means may subsequently become defective.

Furthermore, this invention provides for easy removal of defective fastening means.

Such treadle switches often require replacement. Since the frame is embedded in the roadway, it is thus desirable to separate the treadle switch from the frame and to do so in a minimum of time. Consequently, the particular fastening means is of considerable importance.

Several fastening means have been utilized, in the past, but each has a disadvantage in the replacing of the treadle switch which is overcome by this invention.

One such method for example, includes a bolt which passes through a hole in the treadle switch to cooperate with a nut in the frame. While this method ordinarily permits the convenient fastening and unfastening of the treadle switch to the frame, should the bolt and/ or nut become defective it is difficult to unfasten the treadle switch from the frame; also it is difficult to remove the defective fastening means from the frame so that it may be replaced. 1

Accordingly, it is an object of this invention to provide a means for fastening which permits unfastening of the treadle switch from the frame even though the fastening means may be defective.

It is another object to provide a fastening means which may be easily completely removed when defective or desired so that it may be replaced by a new fastening means.

Another object is to provide improved roadway vehicle detector apparatus which is capable of being conveniently maintained and repaired.

It is another object to provide improved detector apparatus in which the treadle switch may be separated from its associated frame without the prior complete removal of the fastening means.

Another object is to provide a frame having a slot or holes of two different dimensions which permits the passage of a fastening means through one dimension but not through the other dimension for cooperation with a second fastening means to fasten a treadle switch to the frame.

Roadway vehicle detectors may include an elongated rectangular supporting frame structure having a length which is a substantial fraction of the width of a traffic lane; the frame is embedded within the roadway with its length perpendicular to the direction of traffic flow in the lane.

Such a frame member may include two parallel elongated side members extending the length of the frame and spaced apart to determine the width of the detector. The

vside members are connected together and a top supporting surface or pan is formed between the side members, extending the length of the detector and slightly recessed from the top of the side members. The frame is then mounted within the roadway so that the top of the side members is adjacent the top surface of the roadway.

Patented .itme l, 1955 Such roadway detectors may also include an elongated treadle switch which is placed within the recess and supported by the top surface or pan of the frame so that its upper surface is adjacent the roadway surface and capable of actuation by passing vehicles.

The treadle switch may be a unitary structure of several forms well known in the art. One form, as disclosed in US. Patent No. 1,928,472 to Harry A. Wilcox, has an elongated base electrical conducting contact plate having a connecting electrical terminal. Upon the base plate are several insulating spacing members. A second electrical contact plate, which is flexible, bridges the spacing members and is adapted when flexed to contact the first contact plate to complete an electrical circuit. To protect the sec ond contact plate from the effect of weather and passing vehicles while still retaining its flexibility, the surface of the treadle switch adjacent the roadway is covered by a rubber pad. Since the conducting base plate is substantially rigid, it may also be used to perform an additional function of connecting the treadle switch to the roadway or frame as will appear hereinafter. Other types of such switches may be utilized since the details of the switch are not a part of this invention.

Such treadle switches are usually mounted on or connected to the top surface of the frame within the recess, by bolts and nuts or similar fastening or connecting means, for example. Since the treadle switch and frame are subject to the weather as well as frequent operation by successive vehicles, the bolts and nuts often become loose or worn, the switch elements break down and sometimes even the frame cracks resulting in frequent removal and tightening of the bolts and nuts and repair of the frame. Hence, in the past, it has been highly desirable to remove such treadle switches.

In the past, the mounting of such switches may utilize a bolt which may be on or pass through the base contact of the electrical treadle switch, and the nut may be on or in the frame or vice versa, if the parts are to be connected. Since one of the parts, the frame, is generally inaccessible because it is mounted in a concrete roadway, the prior art fixedly attached, beneath the top surface of the frame member, a five-sided box-like nut retaining enclosure which substantially completely enclosed a nut except for an open side which was positioned adjacent to a hole in the frame surface to receive the shank of the bolt., The nut retainer also limited rotation of the nut. The treadle switch having a series of spaced holes on both of the elongated sides of its base electrical contact plate was then placed over the top surface of the frame member; a bolt was then passed through the holes in the base contact plate of the switch to the nut through the frame hole and the open side of the nut retainer box so that tightening the bolt and nut joined the treadle switch and the frame. The nut retainer was substantially completely enclosed at the bottom to prevent concrete from reaching the nut. The frame hole above the open side of the nut retainer was sufiicently large for receiving the bolt but prevented the nut from escaping. Also the nut retainer had a width of sufficient dimension to prevent the nut from turning when tightened by the bolt.

The disadvantage of the above method is that should a nut or bolt become stripped, a blow torch or chisel is required to break the bolt and nut connection so that the treadle switch may be separated from the frame. Moreover, after the connection has been broken, the nut is still locked within the nut-retaining cup; the defective nut cannot be replaced except by a removal of the nut retainer cup which is beneath the top surface of the frame and embedded within the concrete.

These disadvantages are certainly serious ones when it is considered that such vehicle detectors may be mounted in heavily traveled roadways which are a menace to workmen and the closing of which may result in great inconvenience to the public.

Other fastening means such a welding nuts to the frame and using bolts for cooperation with tapped holes in the frame, for example, each have rather obvious disadvantages which are solved by this invention.

In accordance with one embodiment of the present invention, these disadvantages are overcome by using an The nut is then placed through the wide section of the t slot into the retaining enclosure and is moved in the retaining cup to a position below the narrow section of the slot. The treadle switch is then placed on the top surface or pan of the frame and the bolt shank is passed through each hole in the treadle switch into the narrow portion of r the slot where it engages the nut in the retaining enclosure. Tightening of the bolt and nut results in a connection of the frame and vehicle detector.

After the nut is slid below the narrow portion of the slot, a square block of neoprene is inserted through the wide portion of the slot into the retaining enclosure as a precautionary measure for retaining the nuts when the unit is disassembled, as for example during shipping, and for protecting the nut from roadway dirt or grease. Neoprene, unlike rubber, will not crack or decompose in the presence of oil and grease.

Another embodiment of the invention provides two holes in the pan or top surface of the frame above the nut-retaining cup. One hole may be round and the other square or some similar configuration so that only the nut may pass through one hole but not through the other. In this embodiment, a square nut may pass through a square hole but not through a round hole.

Should the nut be stripped, or the bolt break or should it be desired to remove or replace worn nuts; the neoprene block is merely removed, and the nut is slid in the retaining cup from beneath the narrow portion of the slot to the portion below the wide portion of the slot and then manually lifted out of the enclosure.

Another advantage of the invention is that Whereas the prior methods required the complete removal of the fastening means to remove the treadle switch from the frame, this invention permits removal by requiring only a loosening of such fastening means.

For a better understanding of my invention together with other objects reference is made to the following description taken in connection with the accompanying drawings; the scope of the invention is defined in the claims.

FIG. 1 is a perspective View of a treadle switch and its frame as it is about to be encased in a concrete roadway perpendicular to the normal flow of traffic.

FIG. 2 is a partial cross-sectional view along lines 22 of FIG. 1 in which cement has been added to completely enclose the trafiic detector apparatus; the treadle switch has been raised to show that it is separate from the frame and is connected thereto only by the bolt and nut.

FIG. 3 is a perspective view of a frame base plate or pan and the associated nut-retainer box; part of the box is cut away to show the position of the nut.

FIG. 4 is an exploded view of the bolt, nut and nutretaining enclosure of FIG. 2.

FIG. 4a illustrates a cross-section of the spring washers of FIG. 4.

FIG. 5 is a partial sectional view showing a further embodiment of the invention.

FIG. 6 is an exploded view of a side frame and stud associated a U-shaped bracket to form the nut-retainer of FIG. 5.

FIGS. 7, 7a and 7b illustrate several modifications of the slots and holes in the base electrical contact plate of the treadle switch and top surface or pan of the frame.

FIG. 8 illustrates a further embodiment of the invention using two holes of different sizes in the frame base or pan.

FIGS. 9 and 9a illustrate a perspective section of the base electrical contact plate of the treadle switch and a section of the frame base plate or pan of two perferred embodiments of the invention.

FIG. 10 illustrates a third embodiment of the invention.

In FIG. 1 is shown a concrete roadway l in which a trench has been cut for installing vehicle detector apparatus 2. The vehicle detector apparatus includes a frame member 3 and a treadle switch 4. The elongated frame member includes a plurality of horizontal and vertical angle irons welded together and adapted to support the treadle switch. The trench, as shown, is larger than the detector apparatus so that concrete may subsequently be poured into the trench to enclose the sides, ends and bottom of the apparatus in the roadway. In the completed installation, the top surface of the detector apparatus will be adjacent to the top surface of the roadway and its longest dimension will be perpendicular to the direction of passing vehicles.

The treadle switch 4, as best shown in FIG. 2, is an electrical switch of molded insulating and conducting elements. The switch includes a resilient rubber pad 5 and a supporting electrical contact plate 6 both of which are attached to each other by pressure molding or other means well known in the art. The contact plate 6 is a substantially rigid electrical conductor and forms a first electrical contact of treadle switch 4. The second contact 6 of the treadle switch t is also shown in FIG. 2, and as shown in FIG. 2 is a resilient or flexible electrical'contact or contacts within the rubber pad and insulated from the rigid contact as shown in US. Patent 1,928,472 to Harry Wilcox. Other forms of such switches are contemplated within the scope of this invention. A requirement of such treadle switches is that one contact is flexible and the other less flexible, so that the passing of a vehicle will close the contacts and thereby energize an electrical circuit.

U-shaped slots 7, are provided along the length of the rubber pad end clearance holes 7 are provided on base contact plate 6 directly below each such slot. The holes '7 need only be largev enough to receive the shank of bolt 8 while the slot 7 must be sufficiently large to receive the head of the bolt and an accompanying washer, if any.

The frame 3, as shown in FIG. 1, includes two parallel top side members 9, two parallel lower side members '10 and a plurality of supporting stud members 11 for connecting the top and lower members.

The frame members, as shown, are angle irons welded together with the members 9 facing outwardly so that the poured concrete will support the vehicle detector in place while also preventing the concrete adjacent to the frame from cracking.

FIG. 2 is a partial vertical cross section along lines 22 of FIG. 1 to' show the association of the treadle switch with the frame, the relation of the bolt and nut and the position of the apparatus with respect to the roadway.

In FIG. 2, a metallic elongated frame base plate or pan 12 is shown for rigidly connecting together the two top side members 9 such as by welding at 13. The base plate 12 extends substantially the entire length of the detector apparatus, and is recessed from the roadway as is shown. The elongated treadle switch 4 is shown as being adapted to fit within this recess. A supporting rib 15 in the form of an angle iron is welded at 16 and extends substantially the entire length of the detector apparatus so that it is again welded at 17 to an end plate 18. The rib 15 provides additional strength to the frame and particularly to the base plate 12 of the frame; in addition the rib forms one side of a nut-retaining means as will appear hereinafter.

An elongated slot 19 is provided in the frame base plate 12 and includes a narrow portion 19' and a wide portion 19 as is more clearly shown in FIGS. 3 and 4. The narrow portion 19' is only large enough to receive the bolt shank, while the wide portion 19" of the slot is large enough to provide clearance for the nut or similar connecting means.

A bracket member 20 in the form of an L-shaped angle iron is Welded at 21 and 22 to rib 15 and stud 11.

As is clearly shown in the exploded View of FIG. 4, a five-sided nut-retaining box or enclosure is provided below the slot 19 in the pan base plate 12 by the association of bracket member 20 with rib 15 and stud 11. This box retains a nut and permits only limited movement of such nut.

Consequently in FIG. 2, a nut 23 may be placed through the wide portion of the slot 19" into the nutretaining cup and subsequently slid in the nut retainer to a position below the narrow portion 19 of the slot. Neoprene rectangular filler blocks 24 may then be inserted to prevent the nut from sliding out of position or becoming completely lost while in-transit. The width of the box is sufficiently narrow in one dimension to prevent a rectangular nut from turning.

With the nut 23 below the narrow portion of the slot 19, the treadle switch may readily be attached to or detached from the frame by connecting the bolt 8 and nut 23. However, should one of the nuts become worn or stripped so that replacement is necessary, or desirable, the neoprene filler block 24 or blocks can be removed, and the nut 23 slid below the wide portion of the slot 19 and then removed. By the reverse process, .a new nut may then be inserted.

FIG. 3 illustrates, in an exploded view, a broad con cept of the invention. A nut retaining enclosure 25 is shown cut away to clearly show the nut 23 and its relation to the enclosure and the pan or base plate 12. The enclosure may be of any type which will prevent the nut from falling down or sideways to an inaccessible point. It may be a five-sided box as shown, and this box may be made by one combination as will be discussed hereinafter in reference to FIG. 5 or 6 or any other method which would restrict the movement of the nut.

FIG. 4 illustrates in an exploded view the cooperation of the inventive features of FIGS. 1 and 2.

The bracket 2t) and stud 11 when welded or otherwise connected together limit the movement of the nut so that the nut can only move in two directions vertically up or down and horizontally back and forth in one direction only.

The bracket 2% and stud 11 when welded together form four (4) sides of an enclosure including a bottom side and three vertical sides. The width of the bottom side is only slightly larger than the width of the nut 23 so that rotation of the nut or movement of the nut in one horizontal direction is restricted. Therefore, the nut can only be moved in a vertical direction or back and forth to one side. Rib 15 when welded to bracket N and stud 11 forms a fifth side of the enclosure and limits the amount of horizontal sliding of the nut within the enclosure. The five-sided nut-retaining enclosure has its open side positioned below the pan or frame base 12 in line with the slots 19 in such base plate. The pan 12 consequently limits the vertical movement of the nut.

The nut may manually be placed within and removed from the nut retaining enclosure, as was discussed above.

It will be appreciated that these fastener-enclosures are within the frame which has been buried in concrete, and that such enclosures are spaced throughout the frame at points where the treadle switch is to be connected to the frame.

Two annular spring washers 26 which have a concave surface are inserted back-to-back between the nut 23 and bolt 8 so that there will always be tension between the nut and bolt when once tightened; this aids in preventing the bolts and nuts from becoming loose. FIG. 4a illustrates a cross section of such spring washers.

FIGS. 5 and 6 illustrate a part of a second embodiment of the invention using a different frame member and nutretaining assembly from that of the embodiment of FIG. 2. An elongated U-shaped side frame 27 having a top arm 28 and a bottom arm 29 and a lip portion 30 is adapted to be mounted in the concrete 1 so that the top of the lip portion 30 is adjacent to the surface of the roadway. Such a side member will extend substantially the length of the vehicle detector apparatus as did the side member 9 in FIG. 1. Another such side member (not shown) could be positioned parallel to and back-to-back with the first side member 27 so that two lip members 30 would be substantially in the same position as were the two elements 9 in FIG. 1. The two side members 27 could then be directly connected together or suitably spaced by spacing members such as a pan, for example. The height of the lip members would determine the depth of the recess for receiving the treadle switch. The top arms 28 or pan would form the top surface of the frame; the treadle switch would be placed upon the top surface.

The arm 28 contains a slot 30 of similar shape to 19. The nut 23 and bolt 8 are shown in solid lines to show their position when tightened to connect the frame and the contact element. A treadle switch, similar to 4 of FIG. 2, would be placed in the recess provided between the top of lip 30 and arm 28 and fastened thereto by the bolt and nut. The dotted line position of the bolt and nut in FIG. 5 merely shows the position at which the nut is removable.

Supporting studs 31 are placed about the side mem bers 27 to provide additional strength for the side members and assist in providing a nut retaining enclosure, as will appear hereinafter.

FIG. 6 illustrates an exploded view of the nut-retaining enclosure and associated slot of FIG. 5. A five-sided nut enclosure which cooperates with slot 30 for connecting the frame and treadle switch by the bolt and nut is formed by the cooperation of U-shaped member 32, the vertical arm of the side frame member 27 and stud 31 which are welded as shown in FIG. 5.

It will be appreciated that the invention as disclosed in both embodiments is basically a means for unfastening the treadle switch and for easily removing stripped nuts or similar connecting means from a frame which is embedded in concrete. Normally, the bolt 8 must first be removed; then the contact element 4 is lifted off the frame 3; the nuts 23 are then removed by sliding them below the wide portion of the slot from which they are capable of being lifted out of the nut enclosure.

At times, however, both the bolt and the nut are so stripped that turning the bolt will not move the relative position of nut and the two are locked together. In such a case, either the bolt must be cut or broken, or the bolt and nut must be removed as a connected unit. Such dual stripping may occur when the bolts and nuts are slightly loosened. In such a case, by the proper proportioning of the length of the wide portion 19" of the slot 19, a slight tilting of the bolt and not will be sufficient to move the nut in its nut-retainer to a position below the wide hole 19" so that both the nut and bolt, even though still connected, may be lifted with the treadle switch from the frame.

enemas Thus it may be desirable to have the length of 19" longer than its Width.

Several modifications of the hole 7' in plate 6 and the slot in plate 12 of FIG. 2 will now be disclosed having unique advantages in combination with the nut retaining means.

As another alternative for removing a stripped bolt and nut, FIGS. 7, 7a and 7b illustrate the use of slots in the base plate 6 of the treadle switch 4 (rather than the hole '7 shown in FIG. 2) in addition to the slot in the pan or frame base plate 12. In FIG. 7, a slot 33 extends from one outer edge of the base contact plate 6 of treadle switch 4 and is associated with the slot 19 of the pan or frame base plate 12. The dotted line shows the normal position of the bolt and nut. The nut retainer is not shown. If the bolt and nut are stripped and slightly loose, the slot 33 will allow the bolt and nut to be tilted at an angle so that the nut is below the wide portion of the slot in the frame and the bolt head is at the right of 33 or completely out of slot 33. The treadle switch, bolt and nut may then be lifted as a unit; the bolt and nut may subsequently be removed from the slot 33. Also, the slot 33'0f FIG. 7 allows the treadle switch 4 to be moved in one direction. For example, if the bolts on oneof the long sides of the treadle switch are removed, the treadle switch may be moved in that one direction; the bolts in the other side arethen separated from their slot 33, and a stripped bolt and nut in the other side may be removed by vertically lifting them without unfastening the bolt and nut. The resulting time saving and convenience are obvious.

Only one slot 33 and I9 is shown, for convenience of illustration. However, such slots will appear along the entire length of the detector in the same manner as holes '7 appeared in FIG. 2.

FIGURE 7a iilustrates a slot 33A in the base contact 6 of treadle switch associated with the pan or frame base plate 12. The wide and narrow portions of slot 19 in base plate 12 have been reversed with respect to the edge of the frame from that shown hereinbefore. This arrangement allows a sliding of the connected bolt and nut or a sliding of the treadle switch with respect to the frame. In this case the advantage of the open ended slot of FIG. 7 in removing the bolt and nut from the treadle switch is absent. However, such a compromise may be acceptable since during normal operation, there is no chance of the bolts and nuts becoming loose and sliding from the open end of slot 33 as may infrequently occur'in FIG. 7. Slot 19 may be in the same or opposite directions on both sides of pan 12.

FIG. 7b illustrates another method of removing the bolts and nuts. A slot 33B is provided in contact plate 6 of the treadle switch and has the same shape as slot w in plate 12. The loosened bolt and nut may be moved within the slot 33B and removed vertically.

It should be understood that a nut retainer is associated with each of the embodiments of FIGS. 7, 7a and 7b. Therefore, FIGS. 7, 7a and 7b combine the advantages of being able to remove the nut separately as well as when the nut is still connected to the bolt.

While an elongated slot in the frame or pan having wide and narrow portions has been disclosed, it will be appreciated that other shapes of slots and nut retaining enclosures are contemplated within the scope of the invention. Furthermore, while a slot is the preferred form of the invention, one purpose of the slot is to provide two holes, one of which is larger than the other, and in which nut is being slid in the nut-retaining enclosure and when a bolt and nut are being removed as a single piece. If two holes are used, the bolt must be disconnected from the nut before the nut may be removed. However, this disadvantage may be overcome by a frame base plate having a single hole which could have adjustable means; adjustment of such means would provide an increased dimension or dimensions for removing the nut. Such an adjustable single hole device could, of course, be referred to as a slot having a variable length or width or both. Furthermore, although a bolt and nut is shown, other conventional connecting devices are contemplated within the scope of this invention.

. FIGS. 9 and 9a illustrate in broken plan view sections, the relationship of the holes or slots in plate 6 of the treadle switch 4 and the frame base member 12 of the embodiments of FIGS. 2 and 7 respectively. In FIG. 9 the center lines of the holes 7 and the narrow sections of the slots 19 on opposite sides of the treadle switch and frame base plate respectively are both illustrated as separated by a distance S. In FIG. 9a, the center line of the semi-circular portion of the slots have the same spacing as do the narrow portino of the slots on opposite sides of the frame base plate. When the bolts and nuts are tightened along these center lines, the shank of the bolt will be pressed against the ends of the slots thereby substantially limiting the movement of these fasteners when once tightened.

FIGURE 10 illustrates a third embodiment of the invention. The treadle switch 4 is shown above the frame base plate 12; when the treadle switch is lowered, it can be connected by bolts and nuts as in the previous embodiments. The direction of the slots in T2 are shown as being rotated 90 from that of FIGURE 2, for example; the slots extend along the length of the frame. Nutretaining means will be below these slots as in the other embodiments. Two or more additional slots 34 are illustrated in one end of the frame base plate 12; these slots 34 extend across the width of the frame as in the previous embodiments. The treadle switch has clearance holes '7' for receiving. bolts which will be passed through slots 19 to the nuts.

A removeable plate 35 is adapted to be connected to the frame plate 12 in cooperation with slots 34.. When this plate 35 is removed, the treadle switch 4 may be slid lengthwise in the frame so that all of the bolts and nuts are in the wide portion of the slots 19; the bolt and nuts as well as the treadle switch 4 may then easily be removed from the frame.

the nut is normally enclosed by the smaller hole and can be removed only from the larger hole. Hence the frame base plate 12 may include two holes of different dimensions as shown in FIG. 8.

The preferred slot arrangement has several advantages over two such holes. One obvious advantage is that it is cheaper to punch one hole than two. Another advantage is that there is more freedom of movement both when a Having thus described my invention in several preferred embodiments, it will be obvious, to those skilled in the art, that additional modifications are available within the teaching of this invention. Accordingly the invention is defined in the following claims.

I claim:

It. In a traffic detector for roadways, the combination of an easily disconnectible elongated frame member, and a treadle switch, said frame member comprising a top-supporting plate member having individual spaced apertures extending along the length thereof, each individual aperture including two connected openings of different sizes, and a plurality of correspondingly spaced fastener retaining means attached to said top-supporting member under said apertures; disconnectible threaded fasteners having cooperating smaller and larger parts "comparable in size to the respective two connect-ed openings and said fasteners being connectible together through said smaller of the two openings for connecting the frame to the switch, a removable plate mountable on said frame member, mounting means for mounting said removable plate in a fixed position upon said top-supporting plate member; said treadle switch comprising, a first rigid electrical contact plate, a resilient insulator pad supported by and attached to said first rigid plate, a second flexible electrical contact plate secured to a part of the underside of said resilient insulator pad and movable toward said fixed plate for contact therewith, said resilient insulator pad having a plurality of slot openings above said rigid contact plate, these slot openings being aligned with holes in said rigid plate and above corresponding said smaller openings in said top-supporting member, said holes being smaller than said slots to permit passage of only the smaller part of the fasteners, and said first rigid plate being fastened to said frame adjacent to said removable plate when mounted on the supporting member by insertion of the fastener in the 'hole in the rigid contact plate and in the corresponding smaller opening and by coupling the inserted fastener with its associated disconnectible fastener, whereby the mounting of said removable plate on said top-supporting memher in adjacent relation to said rigid plate maintains the treadle switch and fasteners in fixed position along said supporting plate member and the removal of said removable plate permits the sliding of the treadle switch and its associated fastener to the larger opening of said two different size openings.

2. A trafiic detecting switch treadle structure and mounting apparatus therefor comprising an elongated planar traflic switch having a first rigid electrical contact plate, an upper resilient insulator pad attached to said rigid contact plate, a second flexible electrical contact plate secured to a part of the under side of said upper pad and normally spaced from but being movable toward said rigid plate to contact therewith, said upper pad having a plurality of spaced slots and said rigid plate having corresponding spaced holes below said slots and which are smaller than said slots, an elongated supporting frame to be embedded in a roadway for mounting said rigid plate, said frame including two parallel side members connected transversely and having upward extending parts, the transversely connecting par-ts forming a depressed supporting surface lying below the frame to support the switch and said depressed surface part of said frame having pairs of connecting holes of different sizes, the smaller one of each pair of holes approximating the size of the corresponding holes in the rigid plate and the larger hole of said pair being larger than said corresponding holes in the rigid plate, the smaller holes of respective pairs being in predetermined spaced positions corresponding to said holes in said rigid plate, a plurality of first and second threaded connectors each coupled through said corresponding holes and slots to anchor said rigid plate through the smaller holes in said depressed supporting surface of said frame for fastening said switch in said frame, a plurality of connector retaining means with said frame and below said depressed surface thereof under the respective pairs of connected holes of said depressed surface, each said retaining means having walls spaced to provide close clearance for said second connector and permitting movement of said second connector to and from and laterally between the respective connected holes of said pair and adapted at a flat face of said second connector for preventing rotation of said second connector when under the smaller of said related holes, the connected holes permitting removal of said second connector by movement laterally within the retaining means to correspond with the larger of the paired holes when released from fastened condition.

3. A trafiic detecting switch and mounting apparatus therefor as claimed in claim 2, wherein said retaining means includes a U-shaped bracket mounted within the frame with two parallel arms of the bracket spaced for close clearance with the second connector to prevent movement of the second connector in a direction perpendicular to the arms of the bracket.

4. A traific detecting switch and mounting apparatus therefore as claimed in claim 2, wherein said retaining means includes an L-shaped bracket and members forming with said bracket a five-sided box enclosure having one side which restricts the movement of said second connector in the direction to that one side.

5. A traffic detecting switch and mounting apparatus therefor as claimed in claim 2, wherein said retaining means includes a U-shaped bracket having two arms parallel to the surface of the roadway and one of the arms is provided with a pair of holes which are adapted for re ceiving the coupled first and second connector members.

References Cited by the Examiner UNITED STATES PATENTS 1,474,729 11/23 Ogden -475 1,511,542 10/24 Tomkinson 50475 1,546,901 7/25 Jordahl 50475 1,554,559 9/25 Corcoran -1 2,292,948 8/42 Kendall 50477 2,790,874 4/57 Lund et a1. 20086 2,959,647 11/60 Hohmann 200-86 BERNARD A. GILHEANY, Primary Examiner. MAX L. LEVY, Examiner. 

1. IN A TRAFFIC DETECTOR FOR ROADWAYS, THE COMBINATION OF AN EASILY DISCONNECTABLE ELONGATED FRAME MEMBER, AND A TREADLE SWITCH, SAID FRAME MEMBER COMPRISING A TOP-SUPPORTING PLATE MEMBER HAVING INDIVIDUAL SPACED APERTURES EXTENDING ALONG THE LENGTH THEREOF, EACH INDIVIDUAL APERTURE INCLUDING TWO CONNECTED OPENINGS OF DIFFERENT SIZES, AND A PLURALITY OF CORRESPONDINGLY SPACED FASTENER RETAINING MEANS ATTACHED TO SAID TOP-SUPPRTING MEMBER UNDER SAID APERTURES; DISCONNECTIBLE THREADED FASTENERS HAVING COOPERATING SMALLER AND LARGER PARTS COMPARABLE IN SIZE TO THE RESPECTIVE TWO CONNECTED OPENINGS AND SAID FASTENERS BEING CONNECTIBLE TOGETHER THROUGH SAID SMALLER OF THE TWO OPENINGS FOR CONNECTING THE FRAME TO THE SWITCH, A REMOVABLE PLATE MOUNTABLE ON SAID FRAME MEMBER, MOUNTING MEANS FOR MOUNTING SAID REMOVABLE PLATE IN A FIXED POSITION UPON SAID TOP-SUPPORTING PLATE MEMBER; SAID TREADLE SWITCH COMPRISING, A FIRST RIGID ELECTRICAL CONTACT PLATE, A RESILIENT INSULATOR PAD SUPPORTED BY AND ATTACHED TO SAID FIRST RIGID PLATE, A SECOND FLEXIBLE ELECTRICAL CONTACT PLATE SECURED TO A PART OF THE UNDERSIDE OF SAID RESILIENT INSULATOR PAD AND MOVABLE TOWARD SAID FIXED PLATE FOR CONTACT THEREWITH, SAID RESILIENT INSULATOR PAD HAVING A PLURALITY OF SLOT OPENINGS ABOVE SAID RIGID CONTACT PLATE, THESE SLOT OPENINGS BEING ALIGNED WITH HOLES IN SAID RIGID PLATE AND ABOVE CORRESPONDING SAID SMALLER OPENINGS IN SAID TOP-SUPPORTING MEMBER, SAID HOLES BEING SMALLER THAN SAID SLOTS TO PERMIT PASSAGE OF ONLY THE SMALLER PART OF THE FASTENERS, AND SAID FIRST RIGID PLATE BEING FASTENED TO SAID FRAME ADJACENT TO SAID REMOVABLE PLATE WHEN MOUNTED ON THE SUPPORTING MEMBER BY INSERTION OF THE FASTENER IN THE HOLE IN THE RIGID CONTACT PLATE AND IN THE CORRESPONDING SMALLER OPENING AND BY COUPLING THE INSERTED FASTENER WITH ITS ASSOCIATED DISCONNECTIBLE FASTENER, WHEREBY THE MOUNTING OF SAID REMOVABLE PLATE ON SAID TOP-SUPPORTING MEMBER IN ADJACENT RELATION TO SAID RIGID PLATE MAINTAINS THE TREADLE SWITCH AND FASTENERS IN FIXED POSITION ALONG SAID SUPPORTING PLATE MEMBER AND THE REMOVAL OF SAID REMOVABLE PLATE PERMITS THE SLIDING OF THE TREADLE SWITCH AND ITS ASSOCIATED FASTENER TO THE LARGER OPENING OF SAID TWO DIFFERENT SIZE OPENINGS. 